CHAP. VII.] THE PEAR. 187 



placed on a little hillock ; as no tree is more 

 liable to become cankered from having its 

 collar buried. The tree succeeds best in a 

 deep strong loam, provided it be well drained, 

 and rich rather than poor ; and when the soil 

 appears exhausted, it may be renovated by 

 laying on it what the farmers call a top-dressing 

 of manure, taking care not to bury or even to 

 touch the collar of the tree. Apple trees will, 

 however, nourish in any soil except sand or 

 gravel. They are very apt to become can- 

 kered, and to be attacked by the woolly aphis, 

 sometimes called the American blight (already 

 described in p. 111). Canker is generally 

 caused by some defect in the drainage or the 

 soil, or by planting too deep, and, of course, 

 no remedy can be efficacious till the cause of 

 the disease is removed : when, however, the 

 soil has been renovated or drained, the effects 

 of the disease may be obviated by heading 

 down the tree, when it will produce new and 

 healthy branches ; or by cutting out the cankered 

 part, if it should be so low as to make it in- 

 convenient to cut off the trunk of the tree 

 below it. The American blight is best cured 

 by brushing the parts infested all over with 

 soft soap and water; and repeating the opera- 

 tion whenever any fresh insects appear. 



The Pear. — The culture of the pear, as a 

 standard, differs very little from that of the 

 apple; and, though it is naturally rather a 

 deeper-rooted plant, it requires its fibrous roots 

 to be kept near the surface. There is a general 

 complaint in gardens against pear trees as bad 

 bearers, and very healthy-looking trees have 



